Please use this identifier to cite or link to this item: https://doi.org/10.1117/12.819892
Title: Using liquid crystals as optical gas sensors to detect thiol vapors
Authors: Xu, H. 
Yang, K.-L. 
Keywords: 5CB
Gas sensor
Liquid crystal
PEI
Thiol
Issue Date: 2009
Source: Xu, H., Yang, K.-L. (2009). Using liquid crystals as optical gas sensors to detect thiol vapors. Proceedings of SPIE - The International Society for Optical Engineering 7356 : -. ScholarBank@NUS Repository. https://doi.org/10.1117/12.819892
Abstract: We show that the optical texture of a layer of liquid crystal 4-cyano-4′-pentylbiphenyl (5CB) supported on a thiolsensitive layer can be applied to detect 1-octanethiol and other vaporous thiols with high specificity. As demonstrated in our ellipsometry and XPS results, a thiol-sensitive layer comprising a layer of (PEI) and copper ions is capable of oxidizing thiols to disulfides and immobilizing them on the surface. Because of the hydrophobic hydrocarbon chain of 1-octanethiol, the immobilization of 1-octanethiol lowers the surface energy. Thus, after a thin layer of 5CB is supported on the surface, the lower surface energy causes 5CB to adopt different orientations in regions where copper ions were deposited. Because 5CB is a birefrigent material, different orientations of 5CB also result in distinct optical textures, which are visible to the naked eye under a pair of polarizers. © 2009 SPIE.
Source Title: Proceedings of SPIE - The International Society for Optical Engineering
URI: http://scholarbank.nus.edu.sg/handle/10635/74806
ISBN: 9780819476302
ISSN: 0277786X
DOI: 10.1117/12.819892
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